Wavelength-division multiplexing

About: Wavelength-division multiplexing is a research topic. Over the lifetime, 25059 publications have been published within this topic receiving 332027 citations. The topic is also known as: WDM.

Two-dimensional optoelectronic tune-switch

Abstract: A communications switch for switching telecommunications signals from input wavelength division multiplexed (WDM) optical fibers to output WDM optical fibers is disclosed. A two-dimensional optoelectronic switch is also described which uses tunable lasers and optical diffractive elements to switch a matrix of input/output gigabaud channels without blocking. As the channels proceed through the switch they are spatially switched among one another first within rows, then within columns, and then again within rows in the matrix. The two-dimensional optoelectronic tune-switch (2DOTS) can realize the functionality of the nonblocking three-stage Clos switch for input/output ports carrying several gigabit/s data streams.

Wavelength monitoring and control assembly for WDM optical transmission systems

Abstract: A compact wavelength monitoring and control assembly for a laser emission source is provided comprising a narrow bandpass, wavelength selective transmission filter element, of Fabry-Perot etalon structure, through which a non-collimated beam from the laser source is directed onto two closely spaced photodetectors. For wavelength stabilization, the differential output of the two photodetectors is used in a feedback loop to stabilize the wavelength of the laser source to a desired target wavelength. Through the angular dependence of the wavelength transmission of the Fabry-Perot etalon, a wavelength variation from the source is converted to a transmission loss, which is different for the two photodetectors, so that the wavelength change is detected as a differential power change. The device functions as an optical wavelength discriminator in which the detector converts optical energy to current for a feedback loop for controlling the light source. A lens may be used to control the divergence of the light incident on the filter element to optimize power transfer. Optionally, wavelength tunability is provided by changing the angle of inclination of the Fabry-Perot etalon relative to the laser source. The system is compact and may be co-packaged within the same package as a laser emission source, overcoming coupling, space and power dissipation problems common with known external semiconductor laser wavelength control units.

Tunable gain equalization using a Mach-Zehnder optical filter in multistage fiber amplifiers

Abstract: Tunable signal gain equalization is demonstrated in three-stage Er/sup 3+/-doped fiber amplifiers using a waveguide type Mach-Zehnder (MZ) optical fiber. A 29-channel multiplexed system is examined where signal wavelengths are positioned from 1.548 to 1.555 mu m. By adjusting the MZ transmittance with the external control current, tunable gain equalization is achieved at the output of each amplifier. >

Protection cycles in mesh WDM networks

Abstract: A fault recovery system that is fast and reliable is essential to today's networks, as it can be used to minimize the impact of the fault on the operation of the network and the services it provides. This paper proposes a methodology for performing automatic protection switching (APS) in optical networks with arbitrary mesh topologies in order to protect the network from fiber link failures. All fiber links interconnecting the optical switches are assumed to be bidirectional. In the scenario considered, the layout of the protection fibers and the setup of the protection switches is implemented in nonreal time, during the setup of the network. When a fiber link fails, the connections that use that link are automatically restored and their signals are routed to their original destination using the protection fibers and protection switches. The protection process proposed is fast, distributed, and autonomous. It restores the network in real time, without relying on a central manager or a centralized database. It is also independent of the topology and the connection state of the network at the time of the failure.

Characteristics of optical duobinary signals in terabit/s capacity, high-spectral efficiency WDM systems

Abstract: Optical duobinary signals have been applied to dense wavelength division multiplexing (WDM) systems with high-spectral efficiency to fully utilize a limited gain bandwidth of about 35 nm (4.4 THz) for an erbium-doped fiber amplifier (EDFA). These signals are one type of partial response signals and have narrower bandwidth than conventional intensity modulation (IM) signals. Thus, the use of these signals should make possible to attain ultradense WDM systems. In this paper, characteristics of optical duobinary and IM signals in ultradense WDM systems are compared through experimental evaluations at 20 Gb/s. High-spectral efficiency of 0.6 b/s/Hz was reached in this demonstration.